Surface acoustic wave actuators have potential for use as small linear actuators due to their advantages of high speed and high thrust driving capabilities with a small size.
Japanese Laid-open Patent No. H10-296186 and an invention introduced on p. 505 of the 10th "Electromagnetic Dynamics" symposium reports disclose means of improving the energy efficiency of conventional surface acoustic wave actuators. FIG. 9 shows a surface acoustic wave actuator disclosed in Japanese Laid-open Patent No. H10-296186. Waveguide 17 is configured in an orbital circuit, and surface acoustic waves are propagated along this orbital circuit, thus improving the energy efficiency for driving slider 18. FIG. 10 shows a surface acoustic wave actuator introduced on p. 505 of the 10th "Electromagnetic Dynamics" Symposium reports. In this surface acoustic wave actuator, four unidirectional interdigital transducers 19 having reflector 100 circulate energy, and two driving electrodes 20 work to replenish only the energy lost by circulation to improve the energy efficiency.
However, the means of improving the energy efficiency in the conventional surface acoustic wave actuators as described above requires a larger area on the vibrator for areas other than the propagating face. The system disclosed in Japanese Laid-open patent No. H10-296186 requires an area equivalent to the propagating face for circulating the surface acoustic waves, and the system disclosed on p. 505 of the 10th "Electromagnetic Dynamics" symposium reports, requires many interdigital transducers, enlarging the area occupied by these electrodes on the vibrator.
The present invention aims to offer a surface acoustic wave actuator with even better energy efficiency while maintaining a small area for that other than the propagating face on the vibrator.